1. Field of the Invention
The present invention is related to a double interface flash memory card, in particular to a double interface SD flash memory card.
2. Description of Related Art
Since the USB (Universal Serial Bus) interface was developed in 1996, it has gradually taken over the position of various conventional transmission interfaces due to its high transmission rate, easy installation, hot-swapping and plug & play features. With a USB interface, the host can be connected to various peripheral equipments, such as scanner, keyboard, printer, etc., without the need of installing drivers. Thus products with USB interfaces are widely used not only in computers (e.g., desktops or notebooks) or peripheral equipment but also in various IA products (e.g., PDA, DSC, MP3 Player, etc.).
In year 2,000, Matsushita, SanDisk, and Toshiba introduced a new “SD Flash Memory Card” standard, which is referred as “Secure Digital Card”. A SD Card comprises of several flash memories, a microprocessor, and a semiconductor circuit. Due to its lightweight, small size, high access speed, and large capacity, the SD card is widely used in peripheral equipment, PDAs, DSCs, MP3 Players, etc., and has become a new portable storage media that has vast market value. The SD card adopts a dedicated SD interface. Though manufacturers of peripheral equipment or information appliances can develop products dedicated used with SD flash memory cards, these products can't meet the requirements of customers to exchange data between them and computer systems (desktops or notebooks) or other digital products communicating with USB interfaces. For example, if a consumer wants to access the data in a DSC with the SD flash memory card and display or edit the data in a computer system or a product with a USB interface, this work can't be done because that there is no corresponding SD interface at the computer system or the digital product described above.
In such cases, the consumers have to buy a flash memory card driver (card reader) or an Adaptor that supports SD cards to exchange data with the computer systems or digital products with USB interfaces. Or they may buy a card having the same transfer interface as that of the computer system as the intermediate media to access the data in the SD card. Both of the two approaches add the cost of the product and the complexity of operation, bringing inconvenience to the interoperability between SD cards and products with USB interfaces.